B-L Violating Nucleon Decay and GUT Scale Baryogenesis in SO(10)

TL;DR

This paper explores how SO(10) grand unified theories naturally produce B-L violating operators leading to unconventional nucleon decays and proposes a mechanism where GUT-scale decays generate a B-L asymmetry that explains the universe's baryon asymmetry, compatible with current observations.

Contribution

It demonstrates that SO(10) GUTs can produce dimension-seven B-L violating operators and links GUT-scale decays to baryogenesis, with testable nucleon decay modes.

Findings

Nucleon decay modes n -> e^-K^+ and p -> ν π^+ are within experimental reach.

GUT-scale decays can generate a B-L asymmetry that survives electroweak processes.

The mechanism is compatible with both SUSY and non-SUSY SO(10) models and aligns with observed baryon asymmetry.

Abstract

We show that grand unified theories based on SO(10) generate naturally the next-to-leading baryon number violating operators of dimension seven. These operators, which violate B-L, lead to unconventional decays of the nucleon such as n -> e^-K^+, e^- \pi^+ and p -> \nu \pi^+. In two-step breaking schemes of non-supersymmetric SO(10), nucleon lifetime for decays into these modes is found to be within reach of experiments. We also identify supersymmetric scenarios where these decays may be accessible, consistent with gauge coupling unification. Further, we show that the (B-L)-asymmetry generated in the decays of GUT scale scalar bosons and/or gauge bosons can explain consistently the observed baryon asymmetry of the universe. The induced (B-L)-asymmetry is sphaleron-proof, and survives down to the weak scale without being erased by the electroweak interactions. This mechanism works efficiently in a large class of non-SUSY and SUSY SO(10) models, with either a 126 or a 16 Higgs field employed for rank reduction. In minimal models the induced baryon asymmetry is tightly connected to the masses of quarks, leptons and neutrinos and is found to be compatible with observations.